This invention relates to the field of torque wrenches. More particularly, this invention relates to the field of pneumatically driven torque wrenches having continuous readout and preset capabilities, although features of the present invention may also be incorporated in a manually operated version of the wrench.
Known prior art torque wrenches, either of the general category of this invention or having specific features of interest, are found in the following U.S. Pat. Nos., which list is set forth in numerical order only and is intended to be illustrative and not all inclusive: Amtsberg et al. 3,538,763; Crooks et al. 3,525,256; Lehmann et al. 3,944,430; States 3,440,908; Loofbourrow 3,401,754; Reynolds 2,764,272; Zimmerman 2,183,633; and Zimmerman 2,144,731.
The wrench of the present invention is designed and is particularly suitable for low and moderate torque loads in the range of from about 50 to about 1000 foot-pounds, although wrenches in accordance with the present invention having greater capacity can, of course, be built. The wrench of the present invention is particularly suitable for use as a replacement for impact type wrenches.
As is well known, impact wrenches are noisy in operation and are inaccurate in regard to their output torques. The output inaccuracy poses a considerable safety hazard; parts can come apart in use if the torque imposed on fastening elements was too low, while bolts can be broken during assembly if applied torque is too high.